This invention relates to the art of applying a lubricant coating to a metallic surface which is to be subjected to non-cutting cold forming. Such lubricating layers are necessary primarily in order to avoid striation of the surface of the workpiece, seizure of the workpiece in the drawing die, and damage to the forming die itself.
In the past, it has been common to provide the lubricant layer on the workpiece via a two-stage process. According to this conventional process, the workpiece is first contacted with a phosphate-containing composition in order to form a phosphate-based deposit on the surface by chemical reaction. Thereafter, the workpiece is contacted with an organic lubricant composition such as a soap melt or solution prior to the actual cold forming. Without the prior phosphate coating, the adhesion qualities of the organic lubricant alone have been found to be unsatisfactory for severe cold forming operations.
As an alternative to this two-stage process, attempts have been made to combine the phosphating composition with the organic lubricant in order that one of the stages may be eliminated. Those systems suggested, however, have been water-based systems containing a dissolved phosphate compound with the organic lubricant component being miscible or emulsified therein. The disadvantage of such compositions is that their stability is very poor. Once the organics and the water-soluble components separate as distinct phases, the composition is no longer useful for its intended purpose.
Numerous addition agents such as long chain amines or amides and phosphoric acid esters have been taught for use in lubricant compositions, but no one has suggested the stable organic phase coating composition of the present invention.